1. Technical Field
The present invention relates to a manually-operated sharpening apparatus, and more particularly, to a sharpening apparatus suited to sharpen dental instruments.
2. Related Art
In dental treatments, various types of bladed dental instruments are employed. Especially, scalers are widely employed for scaling tartar and dental plaque on the teeth and for root-planing periodontal faces of the teeth.
As shown in FIG. 1, a typical scaler 9 is comprised of a handle 9a adapted to be grasped by an operator in his or her hand and a shank 9b extending from the handle 9a and having a distal end portion thereof formed with a bladed portion 9c. The bladed portion 9c has an upper flat face 9d which crosses lateral edges of an peripheral face 9e of the blade, to form two ridge lines, i.e., two tips 9f of the blade.
To meet conditions for dental treatments which vary in dependence on types of dental treatments as well as shapes and parts of the teeth subjected to dental treatments, a distal half of the shank 9b, including the blade 9c, is formed into a simple straight-line shape or a complicated shape which is curved in three dimensions. For instance, the scaler 9 is formed into a hoe type, sickle type, chisel type, or currette type.
In order to efficiently carry out dental treatments such as scaling and root planing to thereby enhance therapeutic effects, it is important to maintain the sharpness of a scaler. Normally, a scaler has a sufficient sharpness if a blade angle .theta. (FIG. 2) thereof formed between the upper face 9d and the peripheral face 9e of the blade falls within a range varying from 70 deg to 80 deg, with the bladed portion 9c of the scaler sharpened satisfactorily.
The sharpness of a blade is liable to be deteriorated during the time the scaler is used for scaling tartar on the teeth or for root-planing the teeth, for instance. Thus, the sharpness of the scaler blade is checked before and during the use of the scaler, and the scaler is sharpened as required to maintain a desired sharpness.
The aforementioned sharpening may be made manually or with use of an electric sharpening apparatus.
Manual sharpening is carried out by an operator by causing a relative movement between the scaler grasped in his or her hand and a sharpening stone held in another hand. Such manual sharpening can be made easily and is hence convenient for the operator to sharpen the scaler blade with ease during the dental treatment. However, manual sharpening requires skills in sharpening the scaler in a manner providing the scaler with an appropriate blade angle. Since the sharpening skills greatly vary among individual operators, it is especially difficult to maintain a suitable blade angle if the same scaler is commonly used and sharpened by a number of operators.
In the case of using an electric sharpening apparatus which typically comprises a sharpening-stone driving section, including an electric motor, for causing a sharpening stone to rotate or rectilinearly move, sharpening is made by depressing the sharpening stone against the scaler. However, the electric sharpening apparatus has several drawbacks. First, the scaler blade can be sometimes sharpened excessively. Further, much time is required for setting. This makes it difficult to carry out sharpening of the scaler with ease during the dental treatment. Moreover, the electric-operated sharpening apparatus is large in size and complicated in structure, and is hence high-priced. In addition, the sharpening apparatus which accommodates therein electric components is difficult to be subject to sterilization in its entirety at a time. Moreover, it is difficult to maintain cleanness of the sharpening stone.